Manual-automatic lens generator



Aug. 5, 1969 .J. M. SUDDARTH ETAL MANUAL-AUTOMATIC LENS GENERATOR 5 Sheets-Sheet 1 Filed Oct. 14, 1965 mvgwrons JOSEPH 577 TH By max suaomm J 2T7URNEY$ Aug. 5, 969 J. M. SUDDARTH ETAL 3,458,956

MANUALAUTOMATIG LENS GENERATOR Filed Oct. 14, 1965 5 Sheets-Sheet 2 INVENTORS PH TI 7' H Ag s0 ART H iM J /W A TTORNEYS g- 1969 I J. M. SUDDARTH ETAL 3,458,956

MANUAL-AUTOMATIC LENS GENERATOR Filed Oct. 14. 1965 5 Sheets-Sheet 4 YLINDER POSITIONING MOTOR BASE POSITIONING MOTOR CLAMP MACHINE MEMBERS GOO LANT MOTOR FIG. 5

SWEEP MOTOR WORK 40 CHLCK l/V VE N 70/? JOSEPH sr/m J4 ax suoonn m ATT RNEYS g- 1969 J- M. SUDDARTH ETAL 8 6 MANUAL-AUTOMATIC LENS GENERATOR Filed Oct. 14, 1965 5 Sheets-Sheet 5 INVENTORS .zosnw ST/TH JACK 5000mm ATTORNEYS United States Patent 3,458,956 MANUAL-AUTOMATIC LENS GENERATOR Jack M. Suddarth and Joe D. Stith, Muskogee, Okla., as-

signors to Coburn Manufacturing Company, Inc., Muskogee, Okla, a corporation of Oklahoma Filed Oct. 14, 1965, Ser. No. 495,827 Int. Cl. B241) 9/14 U.S. CI. 51-33 8 Claims ABSTRACT OF THE DISCLOSURE A lens generator having means to position the lens holding chuck with respect to the abrading cup by providing a disc having a fixed relationship with the edge of the abrading cup and a lug having a fixed relationship with the .chucking member for orienting the chuck with the lens blank and having automatic and manual means to account for the values determined as a result of said orientation.

This invention relates generally to precision grinders and more particularly to apparatus for generating compound surfaces on ophthalmic lens blanks. The invention is an improvement in that type of generator wherein a rotating cup-shaped abrading tool is swung across the face of the lens. In this type of generator, the base or swing curve is determined by the length of the swing radius and the cross curve is determnied by the angular relationship of the abrading tool has with axis of the lens.

An important objective of this invention is to provide a lens generator of the type described wherein the apparatus for controlling the grinding structure is substantially fully automatic while maintaining a capability of manual operation in the event of a misadjustment or irregularity in the automatic control circuitry.

A further objective of the invention is to provide electric controls for setting the desired curves into the machine.

Another important ojective of this invention is to provide a lens surfacing machine having a simplified means for referencing the chuck-supporting tailstock to the abrading tool.

A further important objective of this invention is to provide an adjustable limit switch for promptly ending the grinding sweep in a manner substantially increasing the number of lenses per hour the lens generator can finish.

A still further important objective of the invention is to provide hydraulic clamping mechanisms for securing the adjustable elements of the invention. Clamping is accomplished whether the adjustment settings are made manually or via the automatic control.

A still further objective of the invention is to provide a means for automatically positioning the adjustable elements of the apparatus to desired settings from readily available manually operated dials on a control panel.

A further objective of this invention is to provide a lens generator having the capability of finishing lenses throughout a wide range both plus and minus diopter curves. The apparatus embodying the invention described is capable of finishing a high number of surfaces per hour for a sustained length of time in either the manual or automatic arrangement.

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Another important objective of the invention is to provide a generator which can receive data for the finishing of a subsequent lens while a lens is being finished. This enables the operator to 'prepare for the next grinding operation while a grinding operation is actually occurring.

These and other important objectives and advantages of the invention will hereinafter become more fully apparent from the following description of the drawings illustrating a presently preferred embodiment thereof and wherein:

FIGURE 1 is a side elevational view of the generator;

FIGURE 1a is a diagrammatic perspective of part of FIGURE 1;

FIGURE 2 is a partial cross-sectional view along the line 22 of FIGURE 1;

FIGURE 3 is a partial perspective view of one portion of the invention;

FIGURE 4 is a diagrammatic-schematic view of the automatic control circuitry;

FIGURE 5 is a schematic partially diagrammatic view of the power circuitry of this invention;

FIGURE 6 is a diagrammatic top view of several of the working elements;

FIGURE 6w is an enlarged plan of a portion of FIG- URE 6; and

FIGURE 7 is a perspective showing the deck element tilted away for purposes of clarity.

Referring now more particularly to the drawings wherein like numerals indicate like parts, the numeral 10 indicates the supporting housing of this invention. A chucksupporting assembly 11 and a grinding tool supporting assembly 12 are juxtaposed opposite one another longitudinally along the upper surface of a housing 10. Affixed by screws or the like to one end of housing 10 is 'a tailstock riser 14. Disposed immediately above the riser is a tailstock slide carrier 16. The carrier 16 is mounted for longitudinal, slidable movement toward and away from assembly 12 along dovetail tracks 17 and rails 18 which respectively form the line of juncture between the riser and carrier. Movement of the carrier with respect to the stationary riser is transmitted via a handwheel 20. The handwheel operates a shaft 21 which is rotatably journaled through riser 14. The shaft, at its inner end, carries a pinion 22 which engages a rack 24. The rack 24 depends downwardly from the carrier 16 and extends substantially throughout the longitudinal length thereof. Thus a rotation of the handwheel 20 moves the carrier 16 toward and away from the abrading or tool supporting assembly 12.

Slidably mounted on the upper surface of carrier 16 along a dovetail rail 26 and tracks 27, also for movement toward and away from the chuck assembly 12, is a tailstock 25. The tailstock 25 supports a lens chuck 28 at that end disposed nearest the grinding tool housing 12. At the rear or other end of the tailstock is a knurled knob 30 carrying a threaded shaft 32 which extends into the inte rior of the tailstock. The shaft is received by a threaded journal or adjustment nut 34 which is fixedly secured to carrier 16. Therefore, a rotation of knob 30 causes a longitudinal, back and forth movement of tailstock 25 with respect to carrier 16. Mounted for rotation with shaft 32 and handwheel 30 is a finished thickness scale 38 scored in diopters. Base scale 40 is non-rotatably afiixed to the tailstock. As will become more apparent hereinafter, once a relationship has been established between the face 42 of the lens chuck and the finishing edge of the abrading wheel, the knob 30 is rotated to determine finished lens thickness.

Carrier 16 is locked to tailstock riser 14 via a hydraulic clamp 43 and the tailstock 25 is locked to the riser via the hydraulic clamp 44. Since the clamps are substantially alike, only clamp 43 will be described in detail. Referring to FIGURE 2, it can be seen that a clamp cylinder housing 46 is fitted to the riser in an opening 49 along the longitudinal length of the carrier 16. The clamp is disposed to extend through track 17 at a level opposite rail 18. A gib 48 is placed between the track and dovetail rail. Cylinder 46 carries a reciprocating piston 50 which has an arm portion 51 in engagement with the gib. Upon an application of pressure in hydraulic conduit 54 the arm pushes gib 48 against the dovetail, thus locking members 14 and 16 against movement with respect to one another. Tailstock 25 is likewise locked to carrier 16 by the hydraulic clamp 44.

Extending forwardly of the carrier 16, below lens chuck 28, is a bracket 55 carrying a cylindrical positioning standard 56. The purpose of the positioning standard will be described together with the structure of the tool supporting assembly 12.

As previously stated, the grinding tool supporting assembly 12 is located on base 10 longitudinally opposite the assembly 11. The housing 10 is formed with turret support surface and journal 60 which rotatably receives a downward extension of a main frame 62. The frame is rotatable about an axis 63 of the turret which intersects the vertical longitudinal center plane 69 of the chuck-supporting assembly 11. Mounted on main frame 62 is a base slide 66 carried via a set of tracks 67 and a mating dovetail rail 67. The tracks and rail enable the base slide 66 to move toward and away from assembly 11. A pair of indicia I and I scales are affixed to the base slide 66 for reading with a scale 70 affixed to the slide. Carried at the outer end of frame 62 is a motor 72 whose output is received by a gear box 73. As seen best in FIGURE 1, gear box 73 drives a threaded shaft 74 which is received by a threaded journal 75 fixedly connected to base slide 66. When shaft 74 is rotated by motor 72 all the super structure mounted on base slide 66, including tool T, moves with respect to assembly 11.

Extending upwardly and forwardly from that end of base slide 66 nearest the chuck is a spacer element 76. A pin 78 secured centrally of the spacer provides a pivot point about which a deck 80 is pivotally mounted for movement in a horizontal plane. The deck is generally fanshaped, having its apex drilled at 81 to receive the pin 78. The arcuate end 83 of the top deck 80 is supported on a bearing surface 82 which surface is disposed above base slide 66. The pin 78 passes through the central vertical plane 69 of the assembly 11 and is coaxial with the radius 64' of the curved surface of the abrading tool. A hydraulic clamp 84 similar to those previously described (43 and 44) is provided for fixedly securing the deck 80 at the desired angular disposition with respect to slide 66. This clamp requires no gib. A clamp 85, also similar to clamps 43 and 44, secures the base slide 66 to the main frame 62.

Angularly disposed dovetail rails 86 are formed along the upper surface of the top deck 80 and slidably support, via the rails 86, the abrading or tool-receiving housing 90 and the tool drive motor and gear assembly 92. A pair of dead-stop screw brackets 94 and 94' (94' not shown) at either end of rails 86 are provided to stop the housing and the abrading cup for either location for grinding plus or minus curves. As those skilled in the art are aware minus and plus curves are formed by changing the approach of the abrading cup toward the lens blank. The rotary motion for driving the abrading cup T is taken from a shaft 93. The means for driving the tool are con ventional and form no part of the invention.

A circular disc 96 is located about pin 78 immediately 4 above the deck 80. The center of disc 96 is coaxial with the center of radii of the abrading cup edge 79 and with the axis 64.

In order to relate the abrading wheel edge 79 with the chuck surface 42, the carrier 16 at its inner end is provided with the previously mentioned standard 56. Pivotally supported about the upper end of the standard and extending forwardly thereof is a lug 98. A helical spring 101, having one end secured to the standard and the other to the lug, biases the lug such that its front, arcuate surface 100 is toward the periphery of disc 96. Stated otherwise, the center longitudinal axis of the lug is spring biased to a perpendicular intersection with the vertical center axis 64 of pin 78. Since the distance from the periphery of disc 96 to the abrading edge 79, and the distance from the surface 100 to the face 42 are of known dimensions, the chuck surface 42 of assembly 11 and the abrading surface 79 are accurately located with respect to one another when surface 100 abuts the disc 96.

In adjusting the generator for a patricular lens, lug surface 100 is brought into engagement with the periphery of disc 96 by rotating handle 20. When the two arcuate surfaces are in engagement, a known distance between the tailstock and the chuck support, within very close tolerances, is established. This distance is known regardless of the radial position of deck 80 or the distance between axis 63 and the axis 64.

It is very important during the abrading sweep that no irregularities occur due to the lug 98 striking the disc 96. Although the two elements should just tangentially brush one another during a grinding stroke, engagement can occur because of the vibrations inherent in abrading machines. In order to prevent this, the lug 98 carries a downwardly depending pin which is engaged by a camming member 106 extending forwardly of the spacer 76. The cam 106 is situated to pivot the lug 98 out of the path of disc 96 as the abrading sweep moves therepast. The biasing element 101 re-positions the lug after the tool passes the area of likely engagement.

The movements of the apparatus are accomplished via a network of precision potentiometers having an improved anti-hunt feature. FIGURE 1 discloses a control panel 104 having a cross-curve dial 110 and a base curve dial 111. The dial 110 controls the angular relationship that the center axis of the tool T will have with the lens blank by swinging the deck 80. The dial 112 controls the distance between axes 63 and 64, or radius of swing, by moving base slide 66 toward and away from the lens L. Mechanically attached to the cross-curve dial 110 is a take-off arm 112 (FIGURE 4) movable along a resistance bank 113. One end of the bank is terminated at 114 to first line 116 of a 60 cycle AC. voltage source. The other end of the resistance bank 113 is terminated in line 118 of the source. Line 116 is connected to one terminal of a motor-driven follow-up potentiometer 122 and line 118 to the other terminal thereof. The potentiometer 122 is provided with a slidable take-off arm 123 which is supported on a shaft 119 driven by an electrical motor 120. The opposite ends of take-off arm 112 and the driven arm 123' are connected via a line 121.

Formed on the lower surface of the deck is a position indicating rack 122a meshing with a position indicating gear 125. A second gear 124 on the shaft 126 meshes with gear 129 which is mechanically associated with the potentiometer or resistance bank 122. A worm gear 127 driven by motor 120, and a rack 128 for driving the deck 80 to conform with the setting on dial 110 is provided. In other words, the gear 129 and 127 reflect location electrically and the worm gear 127 drives the deck to the proper location.

Along the length of the line 121 is a primary coil 130 of an iron core coupling transformer 132. A change in voltage in coil 130 develops a signal in the secondary 134 which in turn is reflected in the grids of a dual triode, firststage amplifier 136. A B+ bias is impressed on the plates of the dual triode by a DC. voltage supply 138. The plate output currents of the triode in lines 140 and 142 are reflected on grids 144 and 146 of second stage triodes 148 and 150. The plate currents of triodes 148 and 150 are respectively carried by lines 152 adn 154 which are terminated by the line 116 of the 60 cycle voltage source. The direct current supply rectifier is connected to the common line 118 via a line 156 and the positive side thereof to line 116 via line 158.

Along the length of line 152 is a relay coil 160 about the relay arm 162 and along the length of line 154 is a relay coil 166 circumscribing a relay arm 164. The relay arms are respectively connected to the reversible slide positioning motor 120- through this switching network. The motor therefore is driven in either direction depending on current flow.

If it is assumed that arm 112 is moved to the right along bank 114, it will be apparent the voltage balance in line 12 is upset causing an increased flow of current in coil 13-0. The resulting voltage is reflected in coil 134 and is coupled to the dual triode amplifier tube 136 via their grids. Depending on the direction of current in line 121, flow-through coil 130 causes a plate current in either lines 140 or 142. Assume that increased flow results in flow in line 142, this reduces the potential on grid 146. Flow-through tube 150 is thus increased whereby arm 164 is energized to close contacts 170. Since the potential on grid 144 would decrease, contacts 166 remain open. Therefore, motor 120 is driven in a direction to move arm 123 along bank 122 to a position of balance with respect to arm 112. The position of arm 112 is sensed by gear 129. This location is reflected in the potentiometer of gear 127. The voltage is upset and the deck is driven by motor 120 (through worm 127) until properly positioned. It should be understood that upon a movement of arm 112 to the left, an opposite chain of events occurs to activate the relay arm 166 causing motor 120 to operate in an opposing direction.

The positioning circuitry includes a novel anti-hunt device by providing a resistance 170 and a capacitance 172 in the joint cathode lines of tubes 148- and 150. The resistance 170 and the capacitance 172 are in parallel with one another. Regardless of whether increased flow results in tube 148 or 150 the resistance 170 will cause a charge across capacitance 172 resulting in a positive or detracting bias on the cathodes of tubes 148 and 150. Thus, current flow is lessened. As arm 123 approaches an alignment with arm 112, the error signal is reduced and motor 120 will be stopped short of the alignment position. A current stoppage is caused by the bias developed by resistance 170 and capacitance 172 even though there is not true alignment between arms 123 and 112. The remaining error signal, together with the capacitance bleed-off in networks 170 and 172 causes either the tube 148 or the tube 150 to conduct current and bias itself off, conduct again after bleed-01f, and repeat until the error voltage is at null.

The main power supply circuitry is seen diagrammatically in FIGURE 5. A switch 200 on the control panel has three positions: namely, OFF, CHUCK, and GEN- ERATE. In the OFF position power is supplied to the base positioning motor 72 and cross (cylinder) positioning motor 120 via contact 201 whereby the desired settings can be placed on the machine in response to movements of dials 111 and 112. After an operator places a blocked lens into the chuck 28, the switch 200 is moved to CHUCK causing it to span contacts 201 and 203. This energizes the clamping mechanism of the chuck 28 to firmly secure the lens. Thereafter, the switch is swung to GENERATE wherein there is a bridging of contacts 203 and 204. In this position current is provided to chuck 28, the sweep motor (which powers the entire assembly 12 through a grinding sweep), the coolant motor, and all of the clamping motors. Note, however, that when moved to GENERATE, power is isolated from the base and cylinder positioning motors. As a result, an operator is free to re-set dials 110 and 111 for the next lens without upsetting the sweep of the generating sweep taking place. This is a valuable time-saving feature since operators heretofore were normally idle during actual abrading. As the generation sweep is completed, the normally closed limit switch 206 is opened which stops the sweep and coolant motors and releases the clamping motors. When the abrading wheel assembly is swung back to its starting position, the switch 206 again closes.

The circuitry for manually operating the machine when there is difficulty in the automatic control circuitry is also disclosed in FIGURE 5. In general, plug means are provided to isolate the base and cross-curve controls from the circuitry.

Lines 207 and 209 connect terminal 201 to the base and cylinder positioning motors through a plug. The plug is represented as a switching network 214 having AUTO and MANUAL positions respectively indicated by position M and A. When in AUTO power at terminal 201 is communicated to the base and cylinder motors through terminals 221 and 222, when in MANUAL these terminals are open. For MANUAL operation, a second pair of conduits 218 and 220 are provided to connect the power supply to the base and cylinder motors. Spanning across these lines are switches 208 and 210 operable by the switch 214 which has the two positions and a centerotf position. In AUTOMATIC, the power to the motors flows through lines 207 and 209 as previously described. In MANUAL power is delivered to the motors across llnes 218 and 220. Although shown diagrammatically as only connecting power to the motors in a single direction, the switches are inserted into the circuit for reversible control of the motors in a manner well known to the art.

In operation, a lens blank having a block attached thereto is placed within the chuck 42. The art knows of means for closely relating the front surface of the chuck 42 with the rear surface of the lens to be finished. For instance, see assignees co-pending application, Coburn et al., Ser. No, 285,167, filed Apr. 22, 1963. The deck s swung manually to a starting position such as shown in FIGURE 6. The proper base curve is set by determining the radius of curvature between the turret axis 63 and the axis 64 of the abrading edge 79. The proper cross or cylinder curve is determined by establishing the angle C between the tool axis 250 and the vertical plane 69. This method of determining cross-curves and base curves is well known in the art.

The operator then sets the desired lens thickness by a setting on the knob 30 by moving surface 42 until the proper thickness indicated on dial 38 is opposite the average diopter curve on dial 40. The extent of the base curve will obviously be determined by the length of the radius R between the rotation axis 63 and the edge of the abrading wheel and the extent of the cross-curve will be determined by the angular relationship between the center axis of the abrading tool and the center axis of the lens chuck. In other words, if angle C is increased, the cross-curve is increased and if angle C is decreased, the cross-curve is decreased.

When an operator is about to generate a lens, he places the lens in chuck 28. If automatic grinding is desired, switch 200 is positioned as shown in FIGURE 5 and the switches 214 and the plug are placed on AUTOMATIC. The operator then sets arm 112 of dial opposite as desired cross-curve setting as determined by the lens prescription. As a consequence of this setting, motor will drive arm 123 to a position corresponding to the new position of arm 112. As arm 123 is driven, the gear 127 will position the deck 80 so that gear 123 will cause a balance.

In order to set the correct base curve according to the lens prescription, dial 111 is turned. Circuitry similar to that shown in FIGURE 4 for the cross-curve is connected to the motor 72 so as to rotate the shaft 74 for sliding the base slide 66 in and out an amount necessary to establish the correct distance R between the turret axis 63 and the abrading edge axis 64. After these entries are made on dial 110 and 111, switch 200 is thrown to GEN- ERATE at which time the entire assembly 12 is driven along the path of the line P shown in FIGURE 6. The drive motor is conventional and the means for driving the assembly are not shown.

It should be noted that dials 38 and 40 are very closely related to the abutting members 96 and 100. When slide carrier 16 is brought forward until elements 96 and 100 abut a positive and constant relationship between the diamond wheel and the slide carrier 16 is established. This relationship is constant regardless of the curve values set into the machine. Dials 38 and 40 are a measurement of the sagitta value. One method of determining sagitta value is the fiber ring method fully explained in applicants co-pending application Ser. No. 285,167, entitled Automatic Lens Grinding Machine.

It should also be noted that lead screw 32 is designed to cause the linear movement of tailstock 25. The movement of tailstock 25 is represented as a sagitta value on dial 40. Dial 38, on the other hand, is a millimeter micrometer dial that is adjusted for lens thickness. For instance, if the front curve of the lens is 4 diopters, dial 38 can be used so that any thickness that is placed opposite 4 diopters is the proper thickness control for the 4- diopter sagitta to render the correct lens thickness.

In a general manner, while there has been disclosed an effective and efiicient embodiment of the invention, it should be well understood that the invention is not limited to such an embodiment, as there might be changes made in the arrangement, disposition, and form of the parts without departing from the principle of the present invention as comprehended within the scope of the accompanying claims.

We claim:

1. A lens grinding apparatus of a type having a chuck to secure a lens blank and an abrading cup for sweeping through said blank during an abrading stroke, an improvement in apparatus for positioning said chuck with respect to said abrading cup comprising:

a first support for said chuck,

a second support for said abrading cup spaced longitudinally from said first support,

a substantially fiat lug secured to said first support at a fixed distance from said chuck and extending toward said second support,

a circular disc on said second support having a peripheral surface in the plane of said lug and a center axis, first means to rotate said second support about a second axis parallel to said center axis,

second means to move said lug into engagement with said peripheral surface whereby the distance between said chuck and the center of said disc is known, said lug being rotatably mounted with respect to said first support, biasing means for extending said lug toward said second support and a camming member on said second support, and said camming member being engagable with means on said lug for moving said lug against said biasing means when said abrading cup swings by said lens.

2. The invention recited in claim 1 wherein there are third means independent of said second means to move said chuck with respect to said abrading cup whereby said chuck can be moved to vary said known distance.

3. The invention recited in claim 2 wherein said abrading cup includes an annular abrading edge and said center of said disc is coaxial with a vertical center axis of said abrading edge in a horizontal plane perpendicular to said center axis and passing through the geometric center of said annular edge.

4. A lens generator of the character described comprising:

chuck means for supporting a lens having a surface to be abraded,

a cup-shaped tool having an annular abrading rim,

adjustable apparatus for supporting said rim in abrading relation with the surface of lens to be abraded, said apparatus comprising;

a main frame rotatable about an axis disposed sub- ;tantially parallel to the general plane of said surace,

a slide frame adjustable in a direction toward and away from said general plane of said surface to therl-eby vary the distance between said axis and said too a deck rotatably mounted on said slide frame to vary the angular disposition of said abrading rim with said general plane, and hydraulic clamp means for fixing said deck with respect to said slide frame and said slide frame to said main frame when said main frame is rotated to cause said abrading tool to traverse the surface of said lens, a first motor to drive said slide frame, a second motor to drive said deck, a first manually operated adjustment dial and a second manually operated adjustment dial, electrical circuitry connecting said first motor with said first dial and said second motor with said second dial, a source of power, and said electrical circuitry including power lines connecting said motors to said source, means including said electrical circuitry causing said slide frame and said deck to assume preselected positions selected by said dials.

5. The circuitry defined in claim 4 wherein said last mentioned means includes anti-hunt means for preventing said deck and slide frame from oscillating upon reaching their preselected positions.

6. The circuitry defined in claim 5 wherein said antihunt means is comprised of a pair of electronic amplifiers having a resistance and capacitor disposed in parallel and connected to the cathodes of said electronic amplifiers.

7. A lens generator having a first support for a lens blank, a second rotatable support for an abrading tool, said second support including a base slide movable toward and away from said blank and a deck rotatably adjustable about an axis perpendicular to said deck and generally parallel to the plane of the lens surface to be abraded, comprising:

a first motor to drive said slide,

a second motor to drive said deck,

sweep motor means to rotate said second support about an axis causing said tool to traverse the surface of the lens to be abraded,

locking clamps for securing said slide to said second support and said deck to said slide as positioned by their respective motors,

a first adjustment dial and a second adjustment dial,

electrical circuitry connecting said first motor with said first dial and said second motor with said second dial, said electrical circuitry including,

means for energizing said first and second motors to drive said slide and said deck to preselected positions selected by said dials and switch means alternatively connecting said sweep motor means or said first and second motors, whereby said sweep motor can swing said second support through an abrading sweep while changes to reposition said deck and said slide can be made by the dials of said first and second motors.

8. A lens generator having a first support for a lens blank, a second rotatable support for an abrading tool, said second support including a base slide movable toward and away from said blank and a deck rotatably adjustable about an axis perpendicular to said deck and generally parallel to the plane of the lens surface to be abraded, comprising:

a first motor to drive said slide,

a second motor to drive said deck,

sweep motor means to rotate said second support about an axis causing said tool to traverse the surface of the lens blank to be abraded,

locking clamps for securing said slide to said second support and said deck to said slide as positioned by their respective motors,

a first adjustment dial and a second adjustment dial,

electrical circuitry connecting said first motor with said first dial and said second motor with said second dial, said circuitry including,

means to drive said slide and said deck to positions selected by said dials, switch means alternatively connecting said sweep motor means or said first and second motors, and second switch means for isolating said dials from said electrical circuitry and electrically connecting said dials to other electrical circuitry whereby said first and second motors can position said slide and deck independently of said first mentioned electrical circuitry.

References Cited UNITED STATES PATENTS 2,806,327 9/1957 Coburn 51--33.1 2,955,390 10/1960 Phillips 5l97 X 10 3,117,396 1/1964 Dalton 51-33 3,289,355 12/1966 Coburn et a1. 5l33 ANDREW R. JUHASZ, Primary Examiner 15 G. WEIDENFELD, Assistant Examiner 

